The role of neurosecretory neurons in the pars intercerebralis and pars lateralis in reproductive diapause of the blowfly, Protophormia terraenovae

Microlesions of the brain were made to examine the role of neurosecretory n eurons in the pars intercerebralis (PI) and pars lateralis (PL) in the indu ction of reproductive diapause of the female blowfly Protophornia terraenov ae. Under both diapause-inducing (LD 12:12, 20 degrees C) and diapause-aver ting conditions (LD 18:6, 25 degrees C), the ovaries invariably failed to d evelop when the PI was removed. When the PL was removed bilaterally, the ov aries developed in most of the females, irrespective of the rearing conditi ons. Removal of the PL prevented females from entering reproductive diapaus e. These results show that certain neurosecretory neurons in the PI are nec essary for vitellogenesis, and that the PL contains inhibitory neurons whic h suppress vitellogenesis during reproductive diapause.